Waste heat boiler with boiler walls and wall portions of finned pipes

ABSTRACT

A waste heat boiler in which a support frame which is symmetrical about a central vertical axis has planar wall members supported thereon and forming an enclosure. Each wall member is symmetrical about a central axis and has flow passages with symmetrically located inlets and outlets. Each wall member is reversible on the support frame to present either face to the inside of the boiler and at least some of the wall members are identical so as to be receivable in several places on the frame. The boiler also has a ceiling member which is tiltable and which is also reversible.

United States Patent [1'91 Vollliardt June 4, 1974 WASTE IIEAT BOILER WITH BOILER WALLS AND WALL PORTIONS OF FINNED PIPES [75] Inventor: Frohmut Vollhardt,

Siegen-Birrbach, Germany [73] Assignee: Siegener Aktiengesellschaft Geisweid, Huttentat-Geisweid, I Germany 22] Filed: May 25, 1973 [21] Appl. No.: 363,941

[30] Foreign Application Priority Data May 27, 1972 Germany 2225971 Feb. 17, 1973 Gcrmany....- 2307870 52 U.S. c1. 122/6 A, 165/76, 122/235 A [51] llnL Cl. F22b 37/00 [58] Field of Search 122/6 A, 235 A, 7 A; I 110/98; 165/76 [56] References Cited 3,375,628 4/1968 Connell et a1. 122/6 A 3,406,664 10/1968 Blaskowski 122/7 3.453.087 7/1969 Herp, Jr. et a1 ,1 122/510 Primary Examiner-Kenneth W. Sprague Assistant Examiner--Larry I. Schwartz Attorney, Agent, or Firm-'-Walter Becker member which is tiltable and which is also reversible.

8 Claims, 9 Drawing Figures PATENTEUJUH 42914 I 3.814062 I saw 10F-5 I PAIENTEDJUN- 4 1914 3. 8 l 4 O 2 sum 5 BF 5 1 WASTE HEAT BOILER WITH BOILER WALLS AND WALL PORTIONS OF FINNED PIPES The present invention relates to a waste heat boiler with boiler walls and wall portions of finned pipes and with headers and distributors at the lower and upper pipe ends.

The employment of such waste heat boilers for exploiting the waste gases which form during the waste acid combustion, encounters considerable difficulties. This is due to the fact that even when employing highgrade burners it is not possible in the furnaces to conduct the combustion so completely that no unburned finest acid mist will remain in the waste gas. This acid mist causes a continuous corrosion of the pipes so that the life of the pipes of the boiler will be relatively short in spite of all precautions taken for avoiding acid mist in waste gases. While these drawbacks can be avoided at least in part by making the pipes of the boiler walls very thick, such an arrangement is rather expensive.

It is, therefore, an object of the present invention to provide a waste heat boiler of the above mentioned general type which will make it possible to use the waste gases of waste acid combusting furnaces without encountering the above outlined drawbacks so that a considerably longer lifetime of the pipes will be realized.

These and other objects and advantages of the invention will appear more clearly from the following specification, in connection with the accompanying drawings, in which:

FIG. I is a diagrammatic longitudinal section through a boiler according to the invention.

FIG. 2 represents a section taken along the line II-II of FIG. I and showing two corner connections of the sidewalls of the boiler according to the invention.

FIG. 3 illustrates on a larger scale than that of FIG. 1 two adjacent pipes ofa boiler wall, and also shows the reduction in cross-section as it occurs in view of corrosion during the operation of the boiler.

FIG. 4 shows the connection of the sidewalls of the boiler with a central wall.

FIG. 5 is a top view'of one of the two pivotable pipe surfaces of the boiler ceiling.

FIG. 6 illustrates on an enlarged scale, a cutout of the pipe surface of FIG. 5. 1

FIG. 7 is a side view of the pipe surface of FIG. 5.

FIG. 8 illustrates a partial longitudinal section through the collecting and distributing connection of the pipe surface according to FIGS. 5 7.

FIG. 9 is a cross-section taken along the line IX-IX of FIG. .8.

The waste heat boiler with boiler walls and wall portions of finned pipes and with headers and distributors at the lower and upper pipe ends is, according to the present invention, characterized primarily in that for purposes of operating the boiler with waste gases from the waste acid combustion, the combination of the following features is provided:

I. All walls and wall portions of the steam generator are straight;

2. The shape of the wall portions making up the steam generator is symmetrical with regard to thevertical central axis of the steam generator; 3. All connecting openings within the individual pipe wall sections are located symmetrically with regard 'and wall portions are located symmetrically with regard to the plane of the wall;

6. The boiler frame is statically so dimensioned that 2 wall portions or walls and reinforcements can be removed and exchanged without affecting the stability of the boiler.

The invention is based on the idea of removing the walls or wall portions in an easy manner from the framework, which walls or wall portions corrode quickly by aggressive acid mist. These walls or wall portions are then turned about their vertical central axis and with their non-corroded side are again installed in the framework.

The possibility of turning the boiler walls about their vertical central axis after the walls have been disengaged from the boiler framework, find their equivalent in exchanging the boiler wall or wall portion formed by the pipes, with the respective oppositely located boiler wall or wall portion so that the previous inner side of one wall or wall portion will in the oppositely located position form the outside, whereas the heretofore outer side of the other wall or wall portion will, in its new position, form the inner side of the wall. An analogous arrangement exists when the wall or the wallportion is pivoted or turned about its left or right-hand edge and is shifted into a position which is approximately rectangular to its original position. Also, in this instance, the principle of the invention applies, namely, that after a certain period of operation of the boiler walls or wall portions during which that side of the pipe which faces the interior of the boiler was subjected to a strong corrosion, whereas'the outer side remains unaffected, the unaffected or non-damaged previous outside will become the inside of the boiler walls, and then up to that time, inner side of the boiler wall, will become the outside of the boiler. In this way, it is possible to get by with a considerably lower wall thickness of the boiler wall pipes and the ceiling pipes and to realize a uniform wear of the pipes over their entire cross section so that at the end of an extended period of operation of the pipes, the walls thereof will have worn substantially evenly.

US. Pat. No. 3,406,664 describes a waste boiler for pyritic roasting gases, according to which the boiler walls are covered by heat exchanger surface sections composed of pipes while the water or steam is passed along a winding path through the serially arranged surface sections of the heat exchanger. The transfer from one section to the next is effected by pipes located outside the boiler outside the wall plane so that in view, of these pipes on one hand, and the asymmetry of the parts on the other hand, a turning will no longer be possible.

German Offenlegungsschrift No. 1,776,043 discloses a waste heat steam generator with angle-shaped finned pipes which form an inner chamber for the waste gases. A turning inside out of the pipes is not possible in view of the straight shape of the pipes.

According to a further feature of the invention, the boiler ceiling comprises one or more pipe surfaces which are formed'of finned pipes and which together with their header and distributor connections are turnable about their longitudinal axis and are pivotable about the longitudinal axis of the connection. Whereas the turnability of the tubular surface serves a uniform wear on both pipe sides, the pivotability of the pipe surface about the longitudinal axis of the connection is provided for purposes of cleaning the interior of the boilerr With the above mentioned embodiment of the boiler ceiling according to the invention, the boiler ceiling is preferably formed by hairpin pipes, the ends of which, lead into a subdivided common connection while the dividing partition is arranged in the plane of the hairpin pipes.

Referring now to the drawings in detail, the'boiler framework G rests on feet 1 and supports the boiler 2, which consists primarily of the walls or wall portions 3, 4, 5, 6, 7 and 8, and of the pipe groups 10, 11 in the two sections A and B of the boiler which are formed, by the partition 9. Furthermore, the boiler comprises an upper boiler ceiling formedby two pipesurfaces l2, 13 which are pivotable along circular arcs K, for instance, into the position 13', and also comprises a lower inflow member 14 into the aggressive waste gas passes through the connection 15 into the boiler. Such aggressive waste gas may, for instance, be the waste gas of an acid burning furnace, which waste is loaded with an acid mist. The withdrawal of the waste gases can be effected in a well-known manner from the upper section of the boiler, which may above the boiler ceiling support additional heat exchanger parts Au.

The walls or wall portions 3 9 are formed by pipes 16 which in the plane W of the walls 3 9 (FIGS. and 3) are provided on both sides with fins 17. The fins of adjacent pipes are connected to each other, for instance, by welding, so that a closed surface of fins and alternating pipes is formed. The walls 3 9 are provided with straight walls, which means that the pipes have a plane and no arched or curved surface. Furthermore, the walls or wall portions 3 9 are designed symmetrically with regard to the central axis M (FIGS. 1 and 2). This axis forms the pivot axis, about which the walls or wall portions are turned when the inside has corroded. Correspondingly, the oppositely located walls or wall portions, as for instance, the wall portions 3 and 4, or 4 and 6 may be exchanged in such a way that the outside of the wall portions 7 takes the place of the inside of the heretofore wall portion 3, and the inside of the wall portion 3 takes the place of the inside of the heretofore wall portion 7. A similar result can be obtained by pivoting the wall portions about their righthand or left-hand edge up to the level of the respective adjacent wall portion.

As will be evident from FIG. I, all connecting openings O, for instance, for the pipe groups 10, I1 and entrance hatches E are located symmetrically with regard to the central or pivot axis M and with regard to the wall plane W (FIG. 2).

According to the right-hand side of FIG. 2, those pipes 16a and 16!) which are located at the longitudinal edges of two adjacent pipe wall portions are likewise provided with fins 17a, 17b. These fins are connected to each other at a right angle, for instance, by welding, so that for disengaging the two fins 17a, 17b, and therefore of the respective adjacent walls, it is merely necessary by severing the welding seam at the connecting ing, connecting, supporting, and the like, of the walls or wall portions are located symmetrically with regard to the wall plane W.

The pipes 16 of the pipe walls or pipe wall sections 3 8 have their lower ends respectively lead into a distributing pipe 23 and have their upper ends respectively lead into a collecting pipe 24. Both pipes are provided with corresponding connections 25 forming inlet and outlet connections. The pipes 23, 24 and the connections 25 are located in the plane of the boiler walls or wall portions 3 9 and symmetrically with regard to the central axis M of these walls or parts, and have their lower end connected to a conduit 27 by means of a flange 26.

For exchanging and turning the walls 3 8 or for exchanging the walls with oppositely located or adjacent walls, it is merely necessary to disengage the conduits 27 from the flanges 26 andto disengage the marginal portions of the straight wall boiler walls 3 9 from the adjacent boiler walls or from the framework G. The framework G is so designed that reinforcements and the walls or wall portions 3 to 8 can be removed from the framework without the latter losing its stability. Therefore, it is possible to turn each of the walls or wall portions 3 8 after the loosening of the connecting means located symmetrically to the wall plane of adjacent pipe walls or pipe wall sections from each other or after the loosening of the pipe walls or pipe wall sections from the framework.

By means of the waste gases intermixed with acid mist, the pipes 16 on the inner side of the wall are subjected to a corrosion as a result of which a crosssectional part 21 of the pipes and a cross-sectional part 22 of the webs is eaten away. As a result thereof, the thickness of the pipe wall is reduced to a cross-section Q.

After a certain time of operation, the walls 3-8 are at their longitudinal edges severed from the adjacent walls and from the partition 9 or from the framework. To this end, the holding and connecting means of the walls are loosened which consist of extensions of the outer fins of the outer pipes of a wall or a wall portion (fins 17a, 17b of FIG. 2) or of extensions or fins on the collecting and distributing chambers. Thereupon the walls or wall portions are turned about their longitudinal axis M or about the turning axis or are exchanged so that now that pipe side which heretofore faced the interior of the boiler faces outwardly whereas the sections of the pipes which heretofore were located on the outer side of the boiler now face the interior of the boiler. Then the turned walls or wall portions are fixed in their new location.

If it should happen that also on that side of the pipes which is now located on the inside corrosion occurs which brings about a reduction in'the wall thickness corresponding to the cross sectional part 21, the pipe walls 3-8 will be exchanged.

The boiler ceiling is formed by the two pipe surfaces 12, 13 which consist of hairpin pipes 28 (FIGS. 5 to 7).

These pipes 28 comprise the straight sections 29, 30

and the curved section 31 while the straight sections have their free ends lead into a pipe connection 32 which has its central portion divided by a wall 33 into an upper chamber 34 and a lower chamber 35. The ends 29a, 30a of pipes 29, 30 lead into the chambers 34 and 35 to which end there are provided the bores 36, 37 in the connection 32. The chambers 34, 35 are separated from each other by sidewalls 38, 39.

The two pipe surfaces l2, 13 are pivotable in a well known manner about the longitudinal axis S of the pipe connection 32 in the direction of the arrow K (FIG. 1) from their horizontal position into an opening position 13' in FIG. 1 so that the boiler can be cleaned, and the pipe groups 10, 11 can be removed from the boiler 2 after the two pipe surfaces 12, 13 have been pivoted.

The pipe surfaces l2, 13 are in the same manner as the sidewalls 3-8 and the partition 9 pivotable or tumable about their longitudinal axis L in such a way that the section 30 of the pipes 28 which heretofore faced the interior of the boiler will occupy the position of the pipe section 29, and the pipe section 29 which did not corrode will occupy the position of the pipe section 30.

Similar to the sidewalls 3-8, a fin 40 is provided on each pipe between the pipes 30 while the adjacent fins are connected to each other. The fins 40 on the longitudinal side are similar to the fins 42 on the narrow side detachably connected to the adjacent boiler walls or the other pipe surface so that, when undoing these connections, the pipe surfaces 12, 13 can be turned about their longitudinal axis L.

It is, of course, to be understood that the present invention is, by no means, limited to the particular showing in the drawings but also comprises any modifications within the scope of the appended claims.

What is claimed is:

1. A boiler, especially a waste heat boiler comprising; a dimensionally stable vertical support frame having an inlet at the bottom and an outlet at the top, planar wall members mounted on said frame and connected along the adjacent edges to form an enclosure supported by said frame, said enclosure being symmetrical about the central vertical axis of said frame, each wall member being formed with liquid flow passages therein. inlet means and outlet means for the flow passages of each wall member, said inlet means and outlet means being symmetrically located in respect of the vertical central plane of the respective wall member, header means for each wall member symmetrically located in respect of the central axis of said frame and of the respective wall member and connected to the inlet means and outlet means of the respective wall member, and connecting means connecting the wall members to said frame and also symmetrically located in respect of the central axis of the respective wall members, whereby each wall member can be reversed about the said central axis thereof for selectively presenting the two sides thereof to the inside of the enclosure formed by said wall members.

2. A boiler according to claim 1 in which the location of the inlet means and outlet means and header means and connecting means is identical for at least some of said wall members for permitting the placement thereof in any of several positions on said frame.

3. A boiler according to claim 1 in which each wall member is formed of pipes having fins thereon, the fins of adjacent pipes in a wall member being joined together to form the wall member.

4. A boiler according to claim 3 in which the fins at the adjacent edges of the wall members are joined together to form the enclosure on the frame.

5. A boiler according to claim 1 in which the enclosure includes ceiling .means at the top, said ceiling means including at least one set of horizontal finned pipes, and a distributor pipe connected to said finned pipes at one end, said set of finned pipes being rotatable as a unit about the axis of said distributor pipe.

6. A boiler according to claim 5 in which said set of finned pipes and the distributor pipe are symmetric about an axis perpendicular to the axis of the distributor pipe to permit inversion of the set of finned pipes.

7. A boiler according to claim 6 in which the ceiling means includes two sets of finned pipes and a distributor pipe for each set of finned pipes at the end of the respective set which is remote from the other set.

8. A boiler according to claim 5 in which said set of finned pipes comprise hairpin shaped pipes with the inlets and outlets in spaced relation, said distributor pipe having a longitudinal partition thereon dividing the inside thereof into separate fluid passages, the inlets of said finned pipes being connected to one of said fluid passages and the outlets being connected to the other of said fluid passages. 

1. A boiler, especially a waste heat boiler comprising; a dimensionally stable vertical support frame having an inlet at the bottom and an outlet at the top, planar wall members mounted on said frame and connected along the adjacent edges to form an enclosure supported by said frame, said enclosure being symmetrical about the central vertical axis of said frame, each wall member being formed with liquid flow passages therein, inlet means and outlet means for the flow passages of each wall member, said inlet means and outlet means being symmetrically located in respect of the vertical central plane of the respective wall member, header means for each wall member symmetrically located in respect of the central axis of said frame and of the respective wall member and connected to the inlet means and outlet means of the respective wall member, and connecting means connecting the wall members to said frame and also symmetrically located in respect of the central axis of the respective wall members, whereby each wall member can be reversed about the said central axis thereof for selectively presenting the two sides thereof to the inside of the enclosure formed by said wall members.
 2. A boiler according to claim 1 in which the location of the inlet means and outlet means and header means and connecting means is identical for at least some of said wall members for permitting the placement thereof in any of several positions on said frame.
 3. A boiler according to claim 1 in which each wall member is formed of pipes having fins thereon, the fins of adjacent pipes in a wall member being joined together to form the wall member.
 4. A boiler according to claim 3 in which the fins at the adjacent edges of the wall members are joined together to form the enclosure on the frame.
 5. A boiler according to claim 1 in which the enclosure includes ceiling means at the top, said ceiling means including at least one set of horizontal finned pipes, and a distributor pipe connected to said finned pipes at one end, said set of finned pipes being rotatable as a unit about the axis of said distributor pipe.
 6. A boiler according to claim 5 in which said set of finned pipes and the distributor pipe are symmetric about an axis perpendicular to the axis of the distributor pipe to permit inversion of the set of finned pipes.
 7. A boiler according to claim 6 in which the ceiling means includes two sets of finned pipes and a distributor pipe for each set of finned pipes at the end of the respective set which is remote from the other set.
 8. A boiler according to claim 5 in which said set of finned pipes comprise hairpin shaped pipes with the inlets and outlets in spaced relation, said distributor pipe having a longitudinal partition thereon dividing the inside thereof into separate fluid passages, the inlets of said finned pipes being connected to one of said fluid passages and the outlets being connected to the other of said fluid passages. 